Am designing a website using joomla 2.5.8 but i just got to know of K2 so i downloaded the latest version that is v2.6.2 but when try to create Extra Field Group, Extra Field, User Group and Categories it does not work.Am able to click on the New button but when am ready to save it the button does not work. Please someone should help me.

Secondly, i want to use K2 to create a list of items on my website i.e. on the FrontEnd and an list of the those items in another link but it links to that on the FrontEnd of the website. Thank you.

If you are not able to save categories, extra fields, or extra field groups, check your page for javascript errors, also check the java script settings in the k2 paramaters.
If there are no errors reinstall k2 over the top of your existing installation